Framing systems for shaping a light beam where a number of shutter blades are moved in and out of the light beam in order to adjust the shape of the beam have been known for many years.
Typical framing systems have a number of shutter blades which can be moved in and out of the light beam by a number of actuators. The light beam is shaped/delimited/framed by adjusting the position of each shutter blade relatively to the light beam and thereby achieving the wanted framing of the light beam. The framing systems are typically used in light fixtures such as moving heads, follow spots and spotlights generating a light beam. Such light fixtures comprise a light source generating a light beam and a number of optical components generating different optical effects.
WO9636834, WO03023513, WO07134609, disclose framing systems according to prior art where a number of shutter blades surrounds the light beam and can be moved in and out of the light beam by a number of actuators. The shutter blades and actuators are mounted on a frame support rotatable carried by a base support. These framing systems are used in light fixtures having a light source generating a light beam, a lens system for focusing and/or zooming the light beam and controlling means (CPU; microprocessors, microcontrollers, PLD or the like) for controlling the components of the light fixture. The framing systems according to WO9636834 and WO03023513 do not from a sharp image of the shutter blades when projected onto a target surface by an optical system and do also take up a lot of space inside the light fixture, as the shutter blades are positioned in at least two different planes.
WO07134609 tries to solve this by providing a light assembly comprising at least one light source for generating a beam of light and a framing system. The framing system comprises a number of shutter blades cooperating with a number of motors to move the shutter blades in and out of the light beam. The shutter blades form a merged pile, where the shutter blades in the merged pile are placed with the front area placed over the front area of a first neighboring shutter blade and the front area placed below the front area of the second neighboring shutter blade. Forming the shutter blades in a merged pile leads to a thin assembly, where the operating edges of the shutters are operating substantially in the same plane. The shutter blades are movable mounted and co-operates with motors to move the shutter means in and out of the light beam. The shutter blades comprise a front end to delimit the beam of light and the two toothed sides and interacting with pinions on the motors. One motor is placed in a fixed position, and second motor is movable in a sideward direction. The two motors allow movement and adjustment of the individual shutter blades in order to delimit the light beam.
The framing system disclosed in WO07134609 is however not very useful as it is very hard to manufacture. The toothed sides of the framing blades tend to break during use, especially during longtime use. The shutter blades must further be moved in a very controlled manner, as the shutter blades can be moved in and out the merged pile causing crucial failure of the framing system. This can for instance occur if the corners of two adjacent shutter blades are moved too far away from each other, which results is in fact that the shutter blades get mixed up and will not work properly. It is possible through the software or by introducing mechanicals stops to limit this movement but this will also limit the framing system's flexibility and degree of freedom.